Measurement of $K^- p$ radiative capture to $γΛ$ and $γΣ^0$ for $p_{K^-}$ between 514 and 750 MeV/$c$
S. Prakhov, P. Vancraeyveld, N. Phaisangittisakul, B. M. K. Nefkens, V. Bekrenev, W. J. Briscoe, L. De Cruz, D. Isenhower, N. Knecht, A. Koulbardis, N. Kozlenko… 展开作者
S. Prakhov, P. Vancraeyveld, N. Phaisangittisakul, B. M. K. Nefkens, V. Bekrenev, W. J. Briscoe, L. De Cruz, D. Isenhower, N. Knecht, A. Koulbardis, N. Kozlenko, S. Kruglov, G. Lolos, I. Lopatin, A. Marušić, S. McDonald, Z. Papandreou, D. Peaslee, J. W. Price, J. Ryckebusch, M. Sadler, A. Shafi, A. Starostin, H. M. Staudenmaier, I. I. Strakovsky, I. Supek, T. Van Cauteren
Differential cross sections for $K^-$ radiative capture in flight on the proton, leading to the $γΛ$ and $γΣ^0$ final states, have been measured at eight $K^-$ momenta between 514 and 750 MeV/$c$. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated $K/π$ beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the $γΣ^0$ final state is dominated by hyperonresonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the $γΛ$ final state, on the other hand, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.
Observeration of Radiative Leptonic Decay of the Tau Lepton
利用CLEO II探测器收集的4.68 fb^{-1}的e^+e^-湮没数据，我们研究了τ辐射衰变τ--> μ nu nu gamma和τ--> e nu nu gamma。在τ静止坐标系中，对于10 MeV的最小光子能量，τ辐射衰变到μ子的分支分数为（3.61 ± 0.16 ± 0.35）× 10^{-3}，衰变到电子的分支分数为（1.75 ± 0.06 ± 0.17）× 10^{-2}。分支分数与标准模型的理论预测一致。所有引用的结果都是初步的。
